These symptoms are specific to recording enabled lines on Cisco central recording (RTP-forking with built-in bridge):
- calls are dropped after transfer to a recorded line
- ad-hoc conferences can not be initiated to 2 or more recorded lines
- other call setup related issues
In a typical case, none of the above problems are present when only non-recorded lines are included in call scenarios.
This is caused by codec changes during a recorded phone call.
The Verba Recording System supports G.711, G.722, G.729, iLBC and more (including codec changes), however the built-in bridge used for recording in Cisco phones has a limitation. When the phone starts a recording session using a certain codec, it gets "locked" into that codec.
During recording, an action that would otherwise require a simple codec change, will instead request a transcoder from UCM. If a transcoder can not be provided, the action will fail. Therefore if your UCM network is properly configured for transcoding between regions, this will not be a problem.
This issue is a limitation of the phone system and not the recorder, therefore resolution is always done in the phone system.
The followings can be done by a Cisco UCM expert:
- Switch the codec selection to utilize e.g. G.711 everywhere
- Implement hardware transcoding between regions